11分之5×20分之1+11分之3×2分之1+11分之5×5分之1
=(11分之5×20分之1+11分之5×5分之1)+11分之3×2分之1
=11分之5×4分之1+11分之6×4分之1
=(11分之5+11分之6)×4分之1
=4分之1
答案:1/4
同时分母都为44可得出
5/11×1/20+3/11×1/2+5/11×1/5
=5/11×1/20+5/11×1/5+3/11×1/2
=(5/11)(1/20+1/5)+3/11×1/2
=(5/11)(1/4)+3/22
=5/44+6/44
=11/44
=1/4
5/11=3/11+2/11
原式=3/11*11/20+2/11*1/20+1/11=37/220